Waste gases are the by-products of various manufacturing processes. Environmental legislation requires, for example, that these wastes be removed from the air before it is released into the atmosphere. Presently, companies employ a system of wet scrubbers to cleanse their manufacturing exhaust of these wastes. The exhaust, for example, is passed up through a wet scrubber consisting of a water tower packed with ceramic rings. Water flows down through the scrubber and absorbs the water soluble gases due to a concentration gradient that favors the absorption of the gases from the exhaust into the water.
The contaminated water is then disposed into the water sewage system and treated usually before being released into the water systems. A rotary biocontactor is one of the devices used to process waste water in the treatment plants. This device requires passing water through a wheel consisting of multiple mesh discs on which a biomass is growing. The biomass converts the carbon waste products into CO.sub.2 instance.
U.S. Pat. No. 3,335,081 discloses an example of this type of rotary biocontactor for treating sewage. A plurality of rotating discs supporting the growth of biomass rotates through the sludge circulated through the apparatus while the upper portion of the discs are exposed to air to thereby provide the necessary oxygen in maintaining the viability of the biological system in degrading the contaminants in the liquid sludge stream.
Other processes involving rotating discs in biological systems are disclosed in U.S. Pat. Nos. 3,594,277 and 4,446,236. Neither of these systems are directed to the removal of pollutants from a gas stream by the use of rotary biocontactor systems.
It is known to purify gases using microorganisms by techniques such as disclosed in U.S. Pat. Nos. 1,701,825, 2,200,581, 2,793,096 and 3,216,905. These systems involve in one form or another contacting a biomass with the waste gas stream to be purified. The waste gases are brought into contact with fine sprays of medium containing the bacteria as disclosed in U.S. Pat. No. 1,701,825. Other techniques of contacting the waste gases with the bacteria include growing the bacteria on supporting media, such as disclosed in U.S. Pat. No. 2,200,581. Soil microorganisms may be used in purifying gases, such as disclosed in U.S. Pat. Nos. 2,793,096 and 3,216,905.
Rotating biocontactors are also used in the production of vaccines such as disclosed in U.S. Pat. Nos. 3,839,155, 3,933,585 and 4,080,258. The systems function in a manner similar to other forms of rotary biocontactors where air or other oxygen containing gas passes over top of the contactor discs to provide the necessary oxygen needed during the metabollic growth of the microorganisms in producing the desired vaccines.